Convert to NAS folder opener HTTP server

- Replace Slint UI with HTTP server using actix-web
- Add CORS support for prism.ccllc.pro
- Implement /open endpoint to open NAS folders in file explorer
- Add /health endpoint for server status
- Support Windows, macOS, and Linux
- Update README with usage instructions

Cargo.toml

@@ -4,7 +4,7 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
-slint = "1.8"
-
-[build-dependencies]
-slint-build = "1.8"
+actix-web = "4.4"
+actix-cors = "0.6"
+serde = { version = "1.0", features = ["derive"] }
+serde_json = "1.0"